Electrical components generate an electromagnetic field when the electrical components are in an activated state. This electromagnetic field can be generated by an act as simple as a current passing through a wire. However, the concern related to the electromagnetic field creating interference is typically related to complex circuitry. This electromagnetic field generated by one component can interfere with the workings of other components in proximity to it. With this concern, various groups and organizations such as the Federal Communications Commission establish requirements regarding the emission of electromagnetic waves or fields from components or units, such as chassises. This emission of electromagnetic waves is typically referred to as electromagnetic interference or EMI.
It is known to create a metal cage surrounding the components to block or "knock down" the radiating electromagnetic waves. As the frequency within the circuitry increases the wavelength decreases, therefore the size of the opening through which the electromagnetic wave can exit the chassis is decreased. For example, as the frequency approaches 622 MHz, the size of the opening through which a wave may pass is in the range of 2 inches. While the height of the wave depends on the frequency, the width or thickness of the wave is infinitesimal. Therefore, while the opening needs to be approximately 2 inches in height for the frequency of approximately 622 MHZ to pass through, the opening could be the thickness of this paper and the wave could pass through.
While there is a desire to reduce the size of openings in the chassis containing the electronic components, there is still a need to access the components and a need to replace components or interchange components as desired. It is known to have a series of panels or plates, such as face plates, which are removable to grant access to a component such as a printed circuit board located within the unit. In addition, the face plate may include openings to allow connectors to be accessible and indicators, such as lights, to be visible from the outside of the unit.
In addition to the desire to limit the emission of electromagnetic waves from the component, there is a desire or need to expel heat from the unit. It is therefore a balance of apparently opposing goals to allow sufficient airflow through the unit to allow proper cooling while at the same time preventing the emission of electromagnetic waves.